%/**
%Focus-vector computation
%@param alpha - elevation, scalar, rad
%@param beta - azimuth, scalar, rad
%@return H - focus-vector
% relevant to antenna's center, 4x1, rad
%*/
function Hv = H( alpha, beta ) 
 k = [cos(alpha)*cos(beta); % Unit vector
 cos(alpha)*sin(beta);
 sin(alpha)];
 r{1} = [0 0 0]; % Antenna's radius-vector, lambdas
 r{2} = [1/2 0 0];
 r{3} = [1/4 -sqrt(3)/4 0];
 r{4} = [-1/4 -sqrt(3)/4 0];
 r{5} = [-1/2 0 0];
 r{6} = [-1/4 sqrt(3)/4 0];
 r{7} = [1/4 sqrt(3)/4 0];
 phi = nan(7,1);
 for i = 1:7
 phi(i) = 2*pi * r{i} * k;
 end

 Hv = exp( 1i * phi );
end 